Need spark plug recommendation

[85_SS_302_Coupe]

I'd like to hear some suggestions on what plug i should run with my combo. I've got a lowish compression 347 with some ported 351 heads. I'm not sure what to look for because of the 351 plug being bigger than the 302 plug. I'm not running spray or anything like that and right now i've got plugs for a 69 mach 1 but i think they're too cold for my stroker. What should i replace them with?

[Jeff88coupe]

Well...an regular autolite 45 is the stock replacement plug....I'd go 1 step colder if you can...that would be a 44.

This thread my help you
http://forums.corral.net/forums/showthread.php?t=436174

[redfirepearlgt]

If you don't mind, I would like to ask a question on this subject. When referringto a spark plug and talking colder vice hotter, what exactly does this mean? Does the colder plug make a bigger spark on the same amount of coil voltage and current? Is the resistance of the plug higher or lower? Is the physical heat generated from the combustion (by the spark) colder or hotter? Am I even in the ballpark with respect top this terminology? Sure would like the true technical breakdown on this other than "you need to run colder plugs when running power adders". Thanks for letting me high-jack to some degree here. I appreciate the feedback. Never to old to learn.

[Dirtyd0g]

I'd run the NGK's because I have had great results with them and they are $2 each. Cheapest platinum plug around I think you would need the Tr55 but you better look it up first.
Alan

[85_SS_302_Coupe]

I wouldn't run a platinum plug if it where free lol. What i need is actual plug part number cause like i said being 351 plugs i really don't know what to look for. I'd also love to hear a break down on heat ranges and what difference they make. All i know is by looking at the porcelin that the ones i have are way colder than most 302 plugs i've handled. Also i'm not entirely sure if the plugs i have where intended for leaded or unleaded since they're for a 6x? Then with this being a 347 i'm just lost. Does anyone think a 93 lightning plug would be good or do those gt40 heads use 302 plugs like the cobra heads did?

[mustang8998]

Maybe this will help you guys!

http://www.centuryperformance.com/spark-plug-tech-spg-26.html

[redfirepearlgt]

Maybe this will help you guys!

http://www.centuryperformance.com/spark-plug-tech-spg-26.html

Thanks JEff, this ios awesome. I never thought about the thermal performance side of the plug. When something is electrically controlled, you just naturally thnk on voltage and current and resistance. Appreciate the link!!!

[85_SS_302_Coupe]

Seems i had it backwards with mine being too cold and i need to go colder. None of the parts places have the autolite 44 so now what?

[redfirepearlgt]

Lots of people go with Brisk. They are Iridium and expensive, but apparently worth the price. Read article on spark plugs that was posted to me by mustang8998. About an hour read for all of it but great enlightenment. Never thought there was so much to a sprak plug.